Process for the manufacture of cyclopentadienyl group iii-a metal compounds



2, ,32 Patented Jan. 2 2 1361 PROCESS FOR THE MANUFACTURE OF CYCLO- PENTADIENYL GROUP III-A METAL COM- POUNDS Jesse R. Maugham, Baton Rouge, La., assignor to Ethyl Corporation, New York, N.Y., a corporation of Dela= ware No Drawing. Filed Apr. 25, 1958, Ser. No. 730,769

5 Claims. (Cl. 260-448) This invention relates to the manufacture of organo compounds of group III-A metals and more particularly to a process for the manufacture of cyclopentadienyl compounds of these metals.

Cyclopentadienyl group III-A metal compounds are useful in the manufacture of cyclopentadienyl compounds of other metals, particularly the transition metals such as manganese cyclopentadienyl compounds. Particularly important of these are cyclopentadienyl manganese tricarbonyl compounds which are extremely effective antiknocks for gasoline used in internal combustion engines. The cyclopentadienyl manganese tricarbonyl compounds are normally manufactured by reacting bis- (cyclopentadienyl) manganese compounds with carbon monoxide. The bis(cyclopentadienyl)manganese compounds can effectively be manufactured by reacting tris- (cyclopentadienyl)aluminum compounds and other group III-A metals, made in accordance with this invention, with manganous compounds, particularly manganous salts, such as the halides, e.g. manganous chloride.

It is, accordingly, an object of this invention to provide an improved process for the manufacture of tris- (cyclopentadienyl) group III-A metal compounds. More particularly, it is an object of this invention to provide an economical process of the above type which provides high conversions to the desired tris(cyclopentadienyl) group III-A metal compounds. A more specific object is to provide a process whereby the tris(cyclopentadienyl) group IIIA metal compounds can be produced directly from the corresponding group III-A metal and particularly a process which does not require elevated pressure and which can be carried out at moderate temperatures. Other objects and advantages of the present invention will become more apparent from the following description and appended claims.

These and other objects of the invention can be accomplished by reacting directly the group III-A metal with a bis(cyclopentadienyl) compound of a group 11-13 metal, i.e. zinc, cadmium and mercury. This process is carried out at a temperature of from about 20 to 150 C., preferably 0 to 100 C. The process is preferably conducted in a liquid media which is a solvent for the bis(cyclopentadienyl) group II-B metal compounds. In the case of the group III-A metals which are solids under reaction conditions, best results are obtained when the metal is subdivided prior to reaction and when the metal is activated either prior to or during reaction.

The effectiveness of the above process in producing tris(cyclopentadienyl) group III-A metal compounds is surprising since the reaction is found to be relatively rapid at very moderate temperatures, that is, Well below the decomposition temperature of the relatively unstable bis(cyclopentadienyl) group II-B metal compounds. Under the conditions of the reaction exceptionally good yields are obtained of the desired group IIIA metal compounds without any appreciable decomposition of either the reactants or the product.

More particularly, the process of this invention comprises reacting a cyclopentadienyl group II-B metal compound with from 1 to about 10 mole equivalents of the group III-A metal. Normally, a more preferred concentration range in from 1 to 6 mole equivalents. An even greater excess of the group III-A metal can be employed and is frequently desired if the excess metal is used for subsequent reactions, as directed below. In actual operation, it is usually convenient to first dissolve the group II-B metal compound in a solvent system and thereafter mix or disperse the subdivided metal in this solution. Alternatively, the metal can be first dispersed in the solvent and the group II-B metal compound added to this dispersion or suspension.

Any of a wide variety of tris(cyclopentadienyl) group III-A metal compounds can be made in accordance with this invention. The cyclopentadienyl radical, for example, can be any cyclomatic radical having the .S-mernber ring found in cyclopentadiene itself. That is, the cyclopentadienyl group can be the cyclopentadienyl radical itself or alkyl or aryl substituted cyclopentadienyl radicals. Furthermore, condensed ring cyclopentadienyl radicals, such as the indenyl and fluorenyl radicals can be employed. The cyclopentadienyl radicals which are most suitable for use in the manufacture of manganese compounds are those containing a total of 5 up to 15 carbon atoms.

Typical examples of cyclopentadienyl group III-A metal compounds which can be made in accordance with this invention are tris(cyclopentadienyDboron, tris (methylcyclopentadienyl) boron, tris(ethylcyclopentadienyl) boron, tris(hexylcyclopentadienyl) boron, tris(octylcyclopentadienyl) boron, bis(cyclopentadienyl)methylcyclopentadienyl boron, tris(phenylcyclopentadienyl)boron, tris- (cyclopentadienyl) aluminum, tris(methylcyclopentadienyl) a.uminum, bis (cyclopentadienyl) methylcyclopentadienyl aluminum, cyclopentadienyl bis(methylcyclopentadienyl)aluminum, tris(1,2 dimethylcyclopentadienyl) aluminum, tris( l,3-methylphenylcyclopentadienyl) aluminum, tris (indenyl) aluminum, tris (fluorenyl) aluminum, tris(cyclopentadienyl)gallium, tris(indenyl)gallium, tris- (cyclopentadienyl) indium, tris (methylcyclopentadienyl) indium, tris(cyclopentadienyl)thallium and tris(fluoroenyl) thallium.

The cyclopentadienyl group 11-13 metal compounds which can be employed in the process of the present in vention correspond to the cyclopentadienyl groups of the above compounds. Thus, in the manufacture of tris- (cyclopentadienyl)aluminum, aluminum metal is reacted with bis(cyclopentadienyl)mercury or other corresponding group II-B metal compound. Similarly, in the manufacture of tris(indenyl)boron, bis(indenyl)zinc or other group II-B metal compound is reacted with boron metal. In the preparation of mixed cyclopentadienyl group III- A metal compounds, a mixed cyclopentadienyl group II- B metal compound can be employed, such as cyclopentadienyl methylcyclopentadienyl mercury or alternatively, bis(cyclopentadienyl) group II-B metal compound, and bis(methylcyclopentadienyl) group II-B metal compound can be reacted simultaneously with a group III-A metal.

The solid group III-A metal is preferably used in a state of subdivision ranging from a powder to metallic chips. In general, the more subdivided the metal is, the more rapid and more complete the reaction. In general, best results are obtained when the solid metal has a particle size ranging from about 1 micron to about 2 millimeters. A particularly suitable method of preparing solid metals for reaction involves forming chips of the metal by passing a massive form of metal into a cutting blade or tool, preferably under the surface of an inert liquid to prevent contamination or oxidation of the metal surface with the air. Contrariwise, the metal may be masses subdivided by atomization, grinding, spraying the molten metal, and the like. A very reactive form of metal can be prepared by alloying the group III-A metal with other metals and particularly useful are amalgams, alloys with copper, and the like.

The metal surfaces can be activated by a variety of procedures. A particularly suitable method is to treat the metal in subdivided form with an organic solvent solution of a hydrogen halide, particularly an ethereal solution of hydrogen chloride or hydrogen bromide. Any ether solution is suitable for this purpose, including aliphatic, aromatic and cyclic ethers. Also suitable are poly ethers of the ethylene glycol type.

Another method of suitably activating group III-A metal treatment is with an organo metallic compound, particularly alkyl metal compounds of groups I-A, ILA and III-A, e.g. lithium aluminum tetraethyl, triethyl aluminum, triisopropyl aluminum, tributyl aluminum, trietlhyl boron, tris(cyclopentadienyl) aluminum, and the A highly reactive form of group III-A metal can be obtained by employing the metal in excess and thereafter reusing the unreacted metal contained in the reaction product residue in a subsequent reaction with the group lL-B metal cyclopentadienyl compound.

The liquid media or solvents suitable for use in the present invention are hydrocarbons, chlorohydrocarbons, amines, ethers, and other liquid media which are inert to the reactants or products. The preferred solvents for the process of this invention are aromatic hydrocarbons and ethers. Typical examples of suitable solvents are hexane, heptane, octane, decane and higher aliphatic hydrocarbons up to about 18 carbon atoms, benzenes, toluene, xylene, mesitylene, ethyl benzene, diphenyl, naphthalene, alkyl naphthalenes, dichlorobenzene, trichlorobenzenes, tetrachlorobenzenes, dimethyl ether, diethyl ether, methyl ethyl ether, dibutyl. ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol methyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and other ethylene glycol dialkyl ethers in which the alkyl groups have from 1 to 10 carbon atoms. Other suitable solvents for this invention are trimethylamine, triethylamine, tributylamine, diethyl aniline, dicyclohexylamine, and the like.

In carrying out the process of this invention, many of the compounds used as reactants and, to some degree, the compounds produced by this invention are reactive to oxygen and/or moisture. For this reason it is preferred to conduct the reaction in the presence of an inert atmosphere, such as dry nitrogen, argon, helium or other non-reactive gases. In some cases, it may be desirable to carry out simultaneously or step-Wise the reaction to form the tris(cyclopentadienyl) group III-A metal compound and convert this compound to the corresponding cyclopentadienyl manganese tricarbonyl compound. Under these conditions it is frequently desirable to use the carbon monoxide employed in the carbonylation reaction as the inert atmosphere.

In conducting the process of the present invention, it is normally desired to agitate the reaction mixture throughout the reaction so as to obtain a rapid reaction rate and to aid in heat distribution and removal from the reaction system. Normally, this can be accomplished by an internal agitator or by bubbling an inert gas through the liquid system. However, if desired, the reactor can be agitated to obtain the desired mixing of the reaction media.

The following examples wherein all parts are parts by weight illustrate the process of this invention:

EXAMPLE I Tris(cyclpentadienyl)aluminum To a reaction vessel equipped with a stirrer and a thermometer, and previously purged. with dry nitrogen was added 8.1 parts (0.302 mole) of finely ground aluminum metal. The aluminum was treated With a diethyl ether solution of anhydrous hydrogen chloride for the purpose of cleaning and activating the surface of the aluminum. The reaction was allowed to continue until all of the metal became dispersed in the foamy mixture. The ether was then removed by three washings with toluene and finally parts of toluene was added as a solvent for the reaction.

With stirring, 25 parts (0.0755 mole) of bis(cyclopentadienyl)mercury Was then added which had been previously prepared according to the method of Wilkinson and Piper, J. Inorg. Nucl. Chem. 2, 32 (1956), from cyclopentadienyl sodium and mercuric chloride. After a 30-minute addition period during which the temperature rose to 45 C., the reaction mixture was stirred for an additional hour at room temperature. A test for mercuric ion in solution was negative.

The reaction mixture was then centrifuged to remove suspended aluminum. Solvent was removed by evaporation at room temperature.

There was obtained 10.7 parts (95.6% yield) of the grey solid tris(cyclopentadienyl)aluminum which melted at 50 to 60 C. It was soluble in benzene and toluene, A portion, on exposure to air, did not spontaneously inflame. Instead, it gradually whitened, indicating formation of aluminum oxide and hydroxide due to attack of atmospheric oxygen and moisture. Upon treatment with Water, white aluminum hydroxide was formed. This was soluble in dilute acid. The pro-duct on aging, stored under nitrogen, showed no tendency to discolor or change in character. The analysis of the product showed 12.1 percent aluminum, the theoretical being 12.24 percent.

The tris(cyclopentadienyl)aluminum (1 mole) prepared above is reacted with stoichiometric quantities of anhydrous manganous chloride at C. in diethylene glycol dimethyl ether (1 mole). The reaction mixture is stirred throughout the reaction. The bis(cyclopentadienyl)manganese so formed is thereafter reacted with carbon monoxide (500 p.s.i.g.) at C. to produce cyclopentadienyl manganese tricarbonyl. This product, after purification by distillation, is then blended in gasoline (0.2 gram manganese metal/ gal. of gasoline) to raise the octane number of the gasoline 2 octane numbers.

EXAMPLE II T ris(methylcyclopentadienyl )aluminum Example I is repeated except that bis(methylcyclopentadienyl)mercury is employed instead of bis(cyclopentadienyl)mercury. Similar results are obtained.

EXAMPLE H1 Tris(indenyl) aluminum Example I is repeated except that bis('indenyl)mercury is employed instead of bis(cyclopentadienyl)mercury, and hexane is employed as the solvent. Very satisfactory yield of the tris(indenyl) aluminum are obtained.

EXAMPLE IV Tris(cycl0pentadienyl) boron Tris(methylcyclopentadienyl) boron Bis(methylcyclopentadienyl)mercury is reacted with metallic boron activated by treating the boron granules with hydrogen bromide dissolved in diethylene glycol dimethyl ether. The reaction is carried out in a triethylamine solvent at a temperature of 50 C. A good yield of the product is obtained.

EXAMPLE VI Trz's(decylcyclopentadienyl) boron Example I is repeated except that bis(decylcyclopentadienyl)mercury is reacted with the excess boron recovered from the preceding example and the reaction is conducted in diethyl ether solvent at a temperature of 20 C. The tris(decylcyclopentadienyl)boron is recovered in good yield.

EXAMPLE VII Cyclopenmdienyl bis(methylcyclopentadienyl) boron good yield.

EXAMPLE VIH T ris( indenyl gallium Example I is repeated except that bis(indenyl)zinc is reacted with gallium metal in the absence of any solvent and at a temperature of about 140 C. The tris(indenyl)- gallium is obtained in very good yield.

EXAMPLE IX Tris(n-octylcyclopentadienyl) indium Indium metal (11.5 parts) is added to 200 parts of n-octylcyclopentadiene. The indium metal is pretreated with aluminum triethyl to activate the metal. The acti- 35 vation is conducted at 70 C. and the indium metal is separated from the excess aluminum triethyl and transferred to the reaction vessel containing the n-octylcyclopentadiene under an inert atmosphere. This reaction mixture is then heated to a temperature of 125 C. for five hours and the tris (n-octylcyclopentadienyl)indium is thereafter recovered in excellent yield by distilling 011 the excess n-octylcyclopentadiene at 1 mm. Hg. pressure.

EXAMPLE X 5 Tris(cyclopentadienyl) thallium Bis(cyclopentadienyl)mercury is dissolved in toluene, reacted with metallic thallium (2 mole equivalents) at reflux temperature. The thallium is activated by preferably treating the granular thallium with tris(cyclopenta- 10 dienyl)aluminum. The tris(cyclopentadienyDthallium is obtained in excellent yield.

I claim:

1. A process for the manufacture of a tris(cyclopentadienyl hydrocarbon) group III-A metal which comprises reacting a group III-A elemental metal with a bis(cyclopentadienyl hydrocarbon) group II-B metal at a temperature of between about to 150 C.

2. The process of claim 1 wherein the group III-A metal is aluminum.

20 3. The process of claim 2 wherein the cyclopentadienyl group contains from 5 to 15 carbon atoms.

4. The process for the manufacture of tris(cyclopentadienyl) aluminum comprising reacting aluminum with bis(cyclopentadienyl)mercury at a temperature of from 20 to 150 C.

5. The process for the manufacture of tris(methylcyclopentadienyl) aluminum comprising reacting aluminum with bis(methylcyclopentadienyl)mercury at a temperature between about --20 to 150 C.

References Cited in the file of this patent UNITED STATES PATENTS 2,818,416 Brown et a]. Dec. 31, 1957 2,831,007 Meister Apr. 15, 1958 FOREIGN PATENTS 1,080,357 France May 26, 1954 OTHER REFERENCES 1956, vol. 2, pp. 32-37. 

1. A PROCESS FOR THE MANUFACTURE OF A TRIS(CYCLOPENTADIENYL HYDROCARBON) GROUP III-A METAL WHICH COMPRISES REACTING A GROUP III-A ELEMENTAL METAL WITH A BIS(CYCLOPENTADIENYL HYDROCARBON) GROUP II-B METAL AT A TEMPERATURE OF BETWEEN ABOUT -20 TO 150*C. 